That thread got me thinking about inflight refueling. I read that AF1 is able to refuel inflight - probably the only 747 (military versions have a different designation that I forget).
Inflight refuel must be one of the hardest duties for pilots in highly maneuverable fighter jets. The fuel tanker is large and fairly static in relation to the fighter jet, but they need to fly in extremely close formation for some (I have no idea how much) time and handle any turbulence generated by the tanker.
A 747 is not easily maneuverable. It is also very big, probably larger than the tanker itself. Flying giant plane close together must be even more challenging than the tanker/fighter combination because both planes are slow to react.
So how do the pilots of AF1 train for this? I cant imagine that they do a quick test run while Mr. Trump is on the 2nd hole, so they can be back by the time he’s on the 17th. And the Air Force is not going to risk the most expensive (probably) aircraft in the world for training.
Lots and lots of simulator time. There are a few assumptions in your post, I think, that may have you thinking the process of air refueling a VC-25 is especially challenging.
First, the USAF refuels in flight comparably large aircraft all of the time, like B-52s, B-2s, and C-5s. Second, while formation flying is required to successfully perform air to air refueling, and the slipstream and jet wash can make things tricky, in the USAF, the boom operator in the tanker is responsible for guiding the refueling boom to the receiving aircraft. It’s not like probe and drogue refueling, where the tanker trails a fuel hose basket, that the receiving aircraft must attempt to attach to with its probe. The USAF’s method strikes me as much easier.
While challenging, it’s a skill that’s uneventfully performed every day by aircraft as large as the VC-25.
The C-5 Galaxy is larger than the VC-25, and there are over a hundred in service. They are capable of in-flight refueling. There are over 200 C-17s which aren’t nearly as big as the VC-25, but they are still incredibly large aircraft. In flight refueling is routine.
More factors than just ease of use can go into the adoption of certain technologies, though.
Cost, for instance. Also ease of maintenance.
Not saying these are necessarily the reason that only the USAF uses it, just challenging the assumption that a technologies lack of wider use refutes claims that it is easier to use.
How many countries operate ‘large’ land-based tanker aircraft? And refuel aircraft the size of, again, large airplanes like strategic bombers or airborne early warning? The Brits do, now with an Airbus A330 derivative, and even they’ve gone to boom and receptacle refueling. See the picture at the wiki: Airbus A330 MRTT - Wikipedia I’m impressed they got probe and drogue to work on a 175k-200k pound aircraft like the Vulcan.
Most countries don’t have the global force projection responsibilities the US does, and consequently can make do with later-converted aircraft to tankers. I suspect it’s easier to add a hose reel and tanks than it is to fit a boom, boom operator, and tanks to many aircraft.
The USN didn’t do it because their missions didn’t require large tankers organic to the carrier battle group. (And those that did, they’d be using NATO or USAF tankers anyway) Not to mention the issues with catapult launching aircraft much bigger than the KA-3. The boom and boom operator take up space, and while I could conceive of fitting one in the KA-3 or KA-6, I can’t see it for smaller aircraft.
The US Air Force went with a flying boom system because they thought it could transfer fuel at higher rates than probe and drogue. This was especially important in the 1950s, when the much of SAC was relatively short-legged B-47s. Since they still (as other posters noted) refuel big, thirsty planes, it seems to make sense to keep with the established system. I do believe that some Air Force tankers do have both systems (KC-10s, maybe?).
And for what it’s worth, according to wikipedia, Australia, the Netherlands, Israel, Turkey, and Iran, also use flying boom systems. I’d be curious as to why they went that way.
I’ve read that they train for refueling on an E-4B, which is also a 747-200 and has the refueling hardware in the same spot. They don’t use the spare VC-25 because they don’t want to scuff the paint.
The replacements won’t have the ability to refuel in flight.
No we haven’t. Our Voyager KC2 and KC3 (MRTT) tankers only have probe and drogue refuelling equipment, no booms. The photo in your link is of an Australian MRTT.
Probably cost, yeah, it would be a pretty fundamental alteration. All our current Typhoons (and until recently the Tornado fleet), a few of our C-130s, the A-400Ms (whether they use them yet or not) and our F-35Bs are all fitted with probes, so we had no need to order MRTTs with booms.
There are multiple 747 Air Force 1 planes. 20 odd years ago I saw one doing practice aborted landings. Well that’s what we assumed it was doing. Repeatedly touching down and then going back up to circle around again.
Large aircraft are fueled using a boom system, not the drogues on a hose that fighters can use. The boom has control surfaces and a boom operator seated in the rear of the tanker flies the boom into the receiver on the other aircraft. The pilot taking fuel uses visual aids on the tanker to hold a steady position.
In another lifetime I babysat the final production units of the black-box that the operator uses to fly the boom on the KC-10 tanker. Don’t know much about the boom mechanical details, or operations, but I can probably recall anything you ask about the electronics, the stick, warning lights, modes, etc. The KC-10 boom control was among the earliest of Sperry’s digital flight control systems…everything prior was Analog. The boom seemed like lower risk to try out the newfangled technology.